With the development of a mobile communication system, a long term evolution network (LTE for short) has become a mobile communication network studied by various manufacturers in the 3rd Generation Partnership Project (3GPP for short) organization actively. An objective of the LTE is to provide a low-cost network that can reduce a time delay, increase a user data rate, and increase system capacity and coverage. With the growth of data services, a multi-input multi-output (multi-input multi-output, MIMO for short) technology, as a new technology, is introduced into an LTE system. The application of the MIMO technology makes space become a resource that can be used to improve performance. Two communication parties using the MIMO technology can use multiple antennas at a transmitting end to send signals independently, and receive and restore original information at a receiving end by using multiple antennas at the same time, so that radio channel capacity is increased exponentially. On condition that bandwidth is not increased, spectrum utilization can be increased exponentially. In the MIMO technology, according to channel quality indicator (channel quality indicator, CQI for short) report configuration information sent by a base station, a user equipment (user equipment, UE) needs to report parameters indicated by the configuration information to the base station, for example, a CQI of a radio channel, and a rank indication (RI for short). The base station performs adaptive modulation and coding based on the CQI and the RI that are reported by the UE, so as to adapt to a radio condition. The RI is the number of MIMO layers suggested by the UE according to the radio condition (informally, the number of data channels suggested to be used for data transmission).
However, how a base station and a UE perform adaptive modulation and coding/decoding based on a correct RI separately to use a MIMO function normally is a problem to be solved in the industry.